A controls system and method of print quality control for a printing system. The controls system uses printed output images as a continuous source of data for control processes. An image quality detector is positioned to detect color data in a printed image after the image is fused to a copy sheet. The present invention samples a wide range of colors in the image in order to calibrate a process station and ensure accurate production of color and/or other image quality parameters. The image quality detector examines an output image and compares the appearance of output image to a desired appearance. When an error exists, the printing system adjusts a process station to correct for variations and inconsistencies in a printed image. The detector of the present invention moves to different locations as the image exits from the printing system to sample a range of image quality parameters in the image.